It is possible to control a Remeha boiler (set point, status and so on) using the RS232 port? As far as I've read, everybody is using the OT port (by implementing a gateway). I don't have any OT thermostat (nor gateway) thus I want to control the boiler using an Arduino through a serial connection.

Is there any information available about the serial requests to get/set the boiler parameters? Thank you in advance for any help.

Looks like all the scripts written for the Remeha RS232 port communications only read data from the boiler. I thought this serial port is a decoded OT interface (TTL compatible). Am I wrong? Is this serial interface made "read only" on purpose (by the manufacturer)?

The Recom software (which is using the same serial interface) could not write any settings to the boiler (not by the regular users but the Remeha professionals)?

I've tried to add a further comment to my first post but the messages was in "moderated" stage for a whole day then it just vanished.

Could anyone (mod) tell me why that message was censored? I was just asking if the communication through the RS232 port is "read only" on purpose (manufacturer) or the Recom software could also set/modify some boiler parameters (including the setpoint) if you have "admin" rights.

Also, I was wondering if the RS232 port is just a clone (TTL level) of the OpenTherm port.

Looks like I'll be walking alone (in this thread) for awhile thus I'm going to tell you a little story.

Back in the 2012, I've just discovered this forum (and @Digit blog for that matter) and I was very impressed by the possibilities of fully controlling a HVAC system (Remeha boiler). As I was in the market for a new boiler, I've searched the local dealers and finally bought a Remeha Quinta Pro 45. As a side note, this model is different from the old "Quinta" one, being an updated version (similar to Calenta/Avanta).

Well, I did't have enough time (at that time) to fulfill my dream (remote controlling my boiler over the internet). You may notice my first post back in that period when I was just testing the Recom software and played with the RS232 to TTL interface.

There were some professional changes in my life during that period too hence I was forced to abort this project. The Remeha walked alone through these years with an old "blind" (aka on/off) thermostat but it survived.

Now I finally have the time to finish my project (along with an entire home automation diy system) so here I am, asking for guidance. After all, you guys owe me some help for the decision I've made four years ago! (j/k)

I've read a lot of threads on this matter but, like I've just said, I saw that everyone is using an OT thermostat and a commercially/diy OT gateway interface to do the job. I must confes that I was a little bit disappointed to find that things didn't changed a lot in the mean time and the (easier to build) RS232 interface seems an obsolete and useless option.

So I'm asking it again: is this interface a "read only" one? At least, I want to know if it worth trying to further investigate, based on your past experience.

The way I saw it, it supposed to be just a TTL clone of that Manchester coded OpenTherm interface (the former being more convenient for master/slave operations). Also, the OT port allow a 2-wire communication and a compatible interface with the dumb on/off thermostats while RS232 it's a 3-wire interface. But aren't those commands similar when using RS232 or OT (Manchester) interfaces?

Btw, I only have linux all around me for years thus I could not test/sniff Recom software for now (though a virtual machine could be an option).

Sorry for this long message but I just wanted to explain the time gap (2012 - 2016) between my posts. Thank you once again for your time.

So I'm asking it again: is this interface a "read only" one? At least, I want to know if it worth trying to further investigate, based on your past experience.

....

From what I have found out, it is for all intents and purposes read only. What you'd be wanting to do (change setpoint, temperature, etc.) is apparently not possible through this interface. Just go ahead and buy/build an OTGW and you'll be set to go.

rjblake wrote:From what I have found out, it is for all intents and purposes read only. What you'd be wanting to do (change setpoint, temperature, etc.) is apparently not possible through this interface. Just go ahead and buy/build an OTGW and you'll be set to go.

Just saw this thread. You are not alone.I control an Avata and a Quinta through the RS232 TTL port. For both units I bought the serial interface but I could have built them myself as well since the hardware seems very easy to build.I mainly read from the bus and used the Recom software to sniff all the messages. I use the FS20 system for all my radiators and control the units on and off using the thermostat overtime switch connected with two relais to my system.I built somekind of proportional heat request system to control the quinta's output temperature. I many FS20 radiator valves are open, the units output is raised and vise versa ranging between 55 and 90 degrees C of output heat. That is about the only thing I write to the bus using these messages to the quinta:

While on the subject of the RS232 port, has anyone taken a look at the Remeha Smart Service Support tool? I see it has a WiFi interface and curious if it can be connected up to Domotica systems for even more control than Opentherm allows. Alternatively, I'm trying to come up with a device that'll provide a WiFi interface to my Remeha Calenta - just not sure exactly how best to do it

rjblake wrote:While on the subject of the RS232 port, has anyone taken a look at the Remeha Smart Service Support tool? I see it has a WiFi interface and curious if it can be connected up to Domotica systems for even more control than Opentherm allows. Alternatively, I'm trying to come up with a device that'll provide a WiFi interface to my Remeha Calenta - just not sure exactly how best to do it

Some further investigation and I have now hooked up a simple ESP8266 (5V version) with the ESP-Link firmware to the RS232 port and using Realterm have managed to send/receive data to the Calenta. Now need to decipher & map the HEX responses and incorporate these into a script to make them all more humanly readable. If this all works, a cheap ($10.00) and simple solution for controlling my boiler

So the long and the short of it is that the exercise was fairly simple in the end - at least to get the reported data from the Remeha Calenta - no need for fancy Remeha cables as a simple 5VDC ESP8266 will do the exact same job. Wire up to an RJ10 connector and you're in business. I found various resources that had bits of code and info to get a readout from the Calenta and ended up creating the PHP script below for those who want to do the same. There is some Domoticz related code in the script, but can easily be identified and stripped out/changed to update system of your choosing. There are also ID's that are not correct and I'm busy debugging as time allows. After that I'll start working on the counters/locking/blocking data from the Calenta.

Actually, I'm on a short vacation abroad hence I couldn't test the code on my boiler yet. In the mean time, I'll try to find the particular data IDs for Quinta Pro but as I only have a Linux notebook available I am unable to install/extract the Recom .msi application to read the Quinta Pro specific xml file.